Adolph steinheil and edward



sponsern forming pm er Lener- Pmnt No, 199.931; ma Angus-s, une;

February B, 1875.

To all whom it may concern:

Be it known that we, ADOLPH STEINHEIL and Enwsnn STEINnEIL, both of Munich, Bavaria, Empire of Germany, have invented a certain new and useful Improvement in Photographical Portrait Apparatnses and other Optical Instruments, of which the following is a specication: v

This improvement relates especially to photographic lenses or combinations of lenses used for the purpose of taking portraits, and is also applicable to such lenses or eombination of lenses when used for other purposes.

All the best photographic lenses, as hereto' fore constructed and used, consist of three lenses arranged separately, a method of construction which causes fifteen reflected images-a result most injurious to the photographic image or picture prodnced,inasmnch as the light becomes considerably troubledor disturbed.

Our invention consists of a novel form and adjustment of the apparatus: by which two lenses only are used, each of which lenses consists of two parts cemented together.

By this method of construction and arrangement greater simplicity is obtained, and only s ix retlected images are produced, and the resulting photographic image or picture is less injuredby the disturbance of the light.

The most essential advantages, however, arising from our novel method of forming and constructing the apparatus consist in the much greater speed with which it operstes, as compared with the best and clearest lenses constructed in the methods ordinarily used and practiced, and that it does not admit any distortion of the photographic image, even on its border edgesf` A Our novel method of formingptographic- .portrait lenses is illustrated in the accom panying drawing, which is a longitudinal section of the apparatus d-d, d, and d3 being the several parts of the lenses, d and dl being cemented together to form one lens, and d and d being cemented together to form the other lens.

The curves of the several glasses which compose tie lenses ditfer from the applanatie lenses for landscapes and groups, as made by us, and in well-known and common use, and also from those well known as Dallmeyers 'v .rectilinear lenses, (which also consist of two fiivipnoysmsnrin PnerisanPmc-"cnMetastasen pairs of cemented lenses,) in not being ground symmetrically and alike, but dissimilar, and in such manner that while the surfaces B and R3 have curves of equal or nearly equal radius, the radius of the surface R* is shortery than that of R, and the radius of R longer than that of R. The first and fourth lenses i' are made of iliut-g1ass, and the second and.

third ofcrown-glass.

The accompanying drawing illustratesvtlloA rule for determining the'curves of the several lenses, and represents an apparatus of 9'! 811'( (nine inches eight and a quarter lines) real focallength,in which R=+45.8; R=:b28.6;

d=2".75; S=60.5; the indices of refraction ofthe glass beinge' A renown. visiones.. Crown......1.5l5l8 1.52530 Flint .......157402 1.59010 The particular size and dimensions shown in the drawing are only in illustration of our, i

oLribn IWL.

lppnass-'msi invention, which may be put inpractice on s. V

larger or smaller scale. .A

By our novel method of forming and ard ranging the lenses more pure and undisturbed images are formed than by any other method, and it is applicable not only to lenses for obtaining photographic portraits, but to lenses used for other optical purposes where bright and undistorted images are required to be produced.

what we claim as new, and desire to secure l by Letters Patent, is-

The arrangement of two lenses, each ofv Y which consists of two partscemented to gether, but which are not formed or ground symmetrically, the surfaceslt* and R having curves ot' equal or nearly equal radius, while the curve R is of shorter radius than that of R, substantially as shown and described.

In testimony that we claim the foregoingt we have hereunto set our hands this 3d day of. December, 1874. 

